The foramen ovale is the congenital communication between the right atrium and left atrium of a heart in utero, allowing oxygenated maternal blood to bypass the lungs of the fetus and go directly to the systemic circulation. It closes completely in the majority of people soon after birth. Studies suggest that there is incomplete closure, called a patent foramen ovale (PFO), in approximately 25 percent of the general population. There appears to be an increased rate of PFO in patients with cryptogenic stroke and migraines suggesting a casual relationship. Closure of a PFO appears to reduce the risk of recurrent stroke and possibly reduces the incidence of migraines. In the past, PFOs were closed surgically with an open chest procedure.
Later, PFOs have been closed in a percutaneous procedure using one of several devices that are considered by the U.S. Food and Drug Administration to be subject to an investigational device exemption (IDE), known as IDE devices. More recently, percutaneous closure of PFOs has become a common procedure. Though randomized study results for its utility are pending, anecdotally it appears that closing a PFO may reduce the risk of recurrent transient ischemic attacks or stroke. In addition, there may be some benefit in treating migraine headaches.
All of the devices used in percutaneous PFO closure share the common feature that for deployment they require left atrial access through the PFO from the right atrium. Routinely, the right atrium is accessed with a catheter through the right femoral vein approach. A catheter, such as a diagnostic catheter, is a tubular structure that is designed to be advanced to various cardiovascular structures, containing a lumen that allows for measurement of pressure, allowing the delivery or removal of a fluid or providing a conduit for a wire. The catheters generally have a preformed distal shape which facilitates access to the desired location. Examples of various preformed catheters used in various other procedures besides percutaneous PFO closure are disclosed in U.S. Pat. Nos. 3,485,234, 5,885,247 and 6,004,280. Standard diagnostic multipurpose catheters are most commonly used for the percutaneous PFO closure procedure, which can usually be accomplished with routine manipulation of the catheter. However, on occasion, the manipulation of the standard multipurpose diagnostic catheter is difficult and can add significant time and risk to the procedure.
Currently there are no catheters designed for the specific purpose of percutaneous PFO closure or for delivering PFO closure devices to the PFO or for other procedures involving access to the left atrium through the PFO. There are transseptal systems for left atrial access, where the transseptal approach is described in Mullins, “Transseptal Left Heart Catheterization: Experience With a New Technique in 520 Pediatric and Adult Patients,” Pediatric Cardiology, 4:239-246, 1983. The devices used in the transseptal approach are designed to puncture the septum and do not pinpoint the appropriate location for a PFO closure device.
The PFO catheter of the present invention overcomes the problems of the prior devices and is well-suited for an efficient percutaneous procedure relating to accessing the left atrium from the right atrium through the PFO, and especially for a PFO closure procedure, while minimizing the risks inherent in such procedures. The catheter facilitates the use of devices used in procedures involving the left atrium where access is gained to the left atrium from the right atrium through the PFO, and particularly a PFO closure procedure using PFO closure devices.